Problem: Subtract. $87 - 68.6 =$
Answer: There are many ways to solve this problem. Let's see two ways we can solve it. Place Value We can think in terms of tenths: $\begin{aligned} &\phantom{=}87-68.6\\\\ &=87.0-68.6\\\\ &=870\text{ tenths} - 686\text{ tenths}\\\\ &=184\text{ tenths}\\\\ &=18.4 \end{aligned}$ Place value table Let's line up the numbers by their decimal places. Tens Ones $.$ Tenths $8$ ${7}$ $.$ ${0}$ $6$ $8$ $.$ ${6}$ Now, let's subtract each place value column. Tens Ones $.$ Tenths $\overset{7}{\cancel{{8}}}$ $\overset{16}{\cancel{{7}}}$ $.$ $\overset{10}{\cancel{{0}}}$ $-$ ${6}$ ${8}$ $.$ ${6}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $1$ $8$ $.$ $4$ $87 - 68.6=18.4$